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// Copyright 2018 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package linux
import (
"math"
"gvisor.googlesource.com/gvisor/pkg/abi/linux"
"gvisor.googlesource.com/gvisor/pkg/sentry/arch"
"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
"gvisor.googlesource.com/gvisor/pkg/sentry/kernel"
"gvisor.googlesource.com/gvisor/pkg/sentry/kernel/auth"
"gvisor.googlesource.com/gvisor/pkg/syserror"
)
const opsMax = 500 // SEMOPM
// Semget handles: semget(key_t key, int nsems, int semflg)
func Semget(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
key := args[0].Int()
nsems := args[1].Int()
flag := args[2].Int()
private := key == linux.IPC_PRIVATE
create := flag&linux.IPC_CREAT == linux.IPC_CREAT
exclusive := flag&linux.IPC_EXCL == linux.IPC_EXCL
mode := linux.FileMode(flag & 0777)
r := t.IPCNamespace().SemaphoreRegistry()
set, err := r.FindOrCreate(t, key, nsems, mode, private, create, exclusive)
if err != nil {
return 0, nil, err
}
return uintptr(set.ID), nil, nil
}
// Semop handles: semop(int semid, struct sembuf *sops, size_t nsops)
func Semop(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
id := args[0].Int()
sembufAddr := args[1].Pointer()
nsops := args[2].SizeT()
r := t.IPCNamespace().SemaphoreRegistry()
set := r.FindByID(id)
if set == nil {
return 0, nil, syserror.EINVAL
}
if nsops <= 0 {
return 0, nil, syserror.EINVAL
}
if nsops > opsMax {
return 0, nil, syserror.E2BIG
}
ops := make([]linux.Sembuf, nsops)
if _, err := t.CopyIn(sembufAddr, ops); err != nil {
return 0, nil, err
}
creds := auth.CredentialsFromContext(t)
for {
ch, num, err := set.ExecuteOps(t, ops, creds)
if ch == nil || err != nil {
// We're done (either on success or a failure).
return 0, nil, err
}
if err = t.Block(ch); err != nil {
set.AbortWait(num, ch)
return 0, nil, err
}
}
}
// Semctl handles: semctl(int semid, int semnum, int cmd, ...)
func Semctl(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
id := args[0].Int()
num := args[1].Int()
cmd := args[2].Int()
switch cmd {
case linux.SETVAL:
val := args[3].Int()
if val > math.MaxInt16 {
return 0, nil, syserror.ERANGE
}
return 0, nil, setVal(t, id, num, int16(val))
case linux.GETVAL:
v, err := getVal(t, id, num)
return uintptr(v), nil, err
case linux.IPC_RMID:
return 0, nil, remove(t, id)
case linux.IPC_SET:
arg := args[3].Pointer()
s := linux.SemidDS{}
if _, err := t.CopyIn(arg, &s); err != nil {
return 0, nil, err
}
perms := fs.FilePermsFromMode(linux.FileMode(s.SemPerm.Mode & 0777))
return 0, nil, ipcSet(t, id, auth.UID(s.SemPerm.UID), auth.GID(s.SemPerm.GID), perms)
default:
return 0, nil, syserror.EINVAL
}
}
func remove(t *kernel.Task, id int32) error {
r := t.IPCNamespace().SemaphoreRegistry()
creds := auth.CredentialsFromContext(t)
return r.RemoveID(id, creds)
}
func ipcSet(t *kernel.Task, id int32, uid auth.UID, gid auth.GID, perms fs.FilePermissions) error {
r := t.IPCNamespace().SemaphoreRegistry()
set := r.FindByID(id)
if set == nil {
return syserror.EINVAL
}
creds := auth.CredentialsFromContext(t)
kuid := creds.UserNamespace.MapToKUID(uid)
if !kuid.Ok() {
return syserror.EINVAL
}
kgid := creds.UserNamespace.MapToKGID(gid)
if !kgid.Ok() {
return syserror.EINVAL
}
owner := fs.FileOwner{UID: kuid, GID: kgid}
return set.Change(t, creds, owner, perms)
}
func setVal(t *kernel.Task, id int32, num int32, val int16) error {
r := t.IPCNamespace().SemaphoreRegistry()
set := r.FindByID(id)
if set == nil {
return syserror.EINVAL
}
creds := auth.CredentialsFromContext(t)
return set.SetVal(t, num, val, creds)
}
func getVal(t *kernel.Task, id int32, num int32) (int16, error) {
r := t.IPCNamespace().SemaphoreRegistry()
set := r.FindByID(id)
if set == nil {
return 0, syserror.EINVAL
}
creds := auth.CredentialsFromContext(t)
return set.GetVal(num, creds)
}
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